BEVERLY HILLS, CA - JULY 31: Filmmaker Ken Burns speaks during the 'Prohibition' panel during the PBS portion of the 2011 Summer TCA Tour held at the Beverly Hilton Hotel on July 31, 2011 in Beverly Hills, California.

Photo: Frederick M. Brown, Getty Images

BEVERLY HILLS, CA - JULY 31: Filmmaker Ken Burns speaks during the...

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"Downtown Abbey II" cast members Michelle Dockery and Dan Stevens pose together for a portrait, Sunday, July 31, 2011, in Beverly Hills, Calif.

Although you really can't watch his extraordinary three-part "Prohibition" documentary without seeing obvious parallels to contemporary debates about the legalization of marijuana, same-sex marriage and the bull-in-the-china-shop impact of the Tea Party movement in American politics, the veteran filmmaker hedges if you try to pin him down about then and now.

Burns, still boyish at 59 (dude, George Harrison is dead and so is his haircut), was the grand finale Sunday of the two-day PBS presentation at the TV Critics Association summer tour.

His documentary factory has turned out some superb films ("Jazz") and some so-so stuff. ("The National Parks" - I'm sorry, my Uncle Morty and Aunt Mimzy's vacation slide show was more interesting: "Here we are at a geyser.")

But regardless of how one feels about the cult of personality that has arisen around Burns, there's no denying that "Prohibition," premiering Oct. 2 on PBS, is absolutely terrific and perhaps the best film yet by Burns and his collaborator, Lynn Novick.

The first hour, which Burns was worried would be seen as "an orphan or a stepchild," because it begins early in the 19th century instead of in the 1920s, is actually the most powerful segment of the documentary, because it tells us how religion and morality attached themselves like an unshakable barnacle to the hull of American politics. Alcoholism was and is a problem in American society, but Prohibition was the most extreme way of dealing with it, and, of course, as history teaches us, destined to fail.

By the second part, we actually get to how the 18th Amendment was passed, thanks to the Anti-Saloon League, which Burns calls the most powerful lobby in American political history, and the resulting social mayhem that we're all somewhat familiar with.

While pussyfooting around the connection between the Prohibition movement and so many potent political issues of the 21st century, Burns essentially says, "We don't make the connection (in the documentary) but you can."

Fair enough, but only a fool would fail to see the links.

Burns' presentation to the TV critics had to be delayed by a day because of the death, last week, of his mentor, Jerome Leibling, his professor at Hampshire College in Amherst, Mass. Leibling taught him that a photographic or cinematic image "contained complex information that did not need to be manipulated" to communicate volumes to the viewer.

Had Leibling not existed or been Burns' mentor, "you would not know me or my films," Burns told the TV critics.

That only adds to the sad irony that the Emmy Awards recognize reality show hosts (Ryan Seacrest! Tom Bergeron!), but have yet to create a separate category for documentaries. That is sinful.

The truth is that some of the greatest filmmaking you'll ever see - not to mention some of the greatest television - is to be found in documentaries on PBS, HBO, Showtime and other channels.

Earlier on Sunday, "Masterpiece" producer Rebecca Eaton trotted out key cast members of the show's ridiculously infectious hit "Downton Abbey," to promote the second season of the British drama, which will premiere Jan. 8 on Colonial TV.

Eaton announced that "Masterpiece" viewership was up by 43 percent this year, thanks to "Downton," the sequel to "Upstairs, Downstairs" and the flabby "Any Human Heart."

Eaton would not reveal the precise day in September that the second season of "Downton" will air on British TV, nor what might happen to any of the major characters. She did say that the second season would be set in 1916, that the character of Gwen, the maid who'd taken typing lessons that led her to get a job as a secretary, would not return, and that the family dog had been sent packing.

No matter. Truth is, "Masterpiece" has racked up 25 Emmy nominations this year, including 11 for "Downton" alone. And for the first time, PBS is actually mounting an Emmy campaign.

HBO is yet to shake in its boots, but to PBS, we can only say, "You go!"

David Wiegand blogs from the TV Critics Association summer press tour on the Culture Blog on SFGate.com.